Drain pump and washing machine having the same

ABSTRACT

A drain pump capable of easily discharging air in the drain pump, and a washing machine having the same. The drain pump includes a washing water inlet compartment, a drain pump compartment configured to pump washing water contained in the washing water inlet compartment to an outside, a suction port provided between the washing water inlet compartment and the drain pump compartment to move the washing water from the washing water inlet compartment to the drain pump compartment, a drain line to connect the drain pump compartment to an outside to discharge the washing water, and an air outlet port provided on the drain pump compartment to discharge air contained in the drain pump compartment to an outside, wherein the air outlet port is connected to the drain line.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Korean PatentApplications No. 10-2011-0098255, filed on Sep. 28, 2011 in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference.

BACKGROUND

1. Field

Embodiments of the present disclosure relate to a washing machine, andmore particularly, to a washing machine provided with a drain pumpconfigured to pump the washing water stored in a tub.

2. Description of the Related Art

A washing machine designed to wash laundry by use of electric power, ingeneral, includes a tub to accommodate a washing water, a rotating tubrotatably installed at an inside the tub, a driving apparatus to rotatethe rotating tub, a water supply apparatus to supply water to an insidethe tub, and a drain pump to forcedly drain water in the tub.

In general, the drain pump includes a pump case provided with a washingwater inlet compartment to accommodate washing water and a drain pumpcompartment, and a pumping motor installed at one side of the pump case.The interior of the pump case is provided at an inside thereof with apump filter to filter foreign substance contained in the washing water.The drain pump compartment is provided with an impeller configured to berotated by the pumping motor.

When the impeller is rotated by the pumping motor, the washing water inthe tub is introduced into the washing water inlet compartment. Thewashing water introduced into the washing water inlet compartment passesthrough the filter, and is withdrawn into the drain pump compartment.The washing water reached to the drain pump compartment is forcedlydischarged to an outside the drain pump by the impeller.

During such a pumping process, air may be introduced into an inside thedrain pump together with the washing water. If the air is introducedinto an inside the pump, the performance of the impeller installed inthe drain pump compartment may be degraded, and thus a drain fault mayoccur or an abnormal noise may be generated.

In general, in order to discharge the air introduced into an inside thedrain pump to an outside, an air outlet port is provided. The air outletport is connected to the tub through a hose. Accordingly, the air at aninside the pump is discharged to a side of the tub through the airoutlet port and the hose.

Since the region where air stays in the drain pump is an upper part ofthe drain pump compartment, the position of the air outlet port isneeded to be adjusted so as to discharge the air.

In addition, there is a need for the air to be discharged to other sidethan the tub provided at an upper side of the drain pump so as toenhance the efficiency of discharging air.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a drainpump capable of easily discharging air thereof to an outside, and awashing machine having the same.

Additional aspects of the disclosure will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

In accordance with one aspect of the present disclosure, a drain pumpincludes a washing water, a drain pump, a suction port, a drain line andan air outlet port. The drain pump compartment may be configured to pumpwashing water contained in the washing water inlet compartment to anoutside. The suction port may be provided between the washing waterinlet compartment and the drain pump compartment to move the washingwater from the washing water inlet compartment to the drain pumpcompartment. The drain line may connect from the drain pump compartmentto an outside to discharge the washing water. The air outlet port may beprovided on the drain pump compartment to discharge air contained in thedrain pump compartment to an outside. The air outlet port is connectedto the drain line.

The air naturally may flow from the air outlet port to the drain linedue to the difference in pressure between the drain pump compartment andthe drain line.

The air outlet port may protrude at an upper portion of the drain pumpcompartment.

The drain pump may further include an air inlet port provided on thedrain line, wherein the air outlet port is connected to the air inletport.

The drain pump may further include an air passage to connect the airoutlet port to the air inlet port.

The air passage may include a rubber hose.

The air inlet port may be integrally formed with the drain line.

The air inlet port may be separately formed with the drain line andcoupled to the drain line.

The drain line may include a drain passage connected to the drain pumpcompartment, and an air passage connected to the air outlet port.

The air passage may be branched from the drain passage.

The air passage may be integrally formed with the drain passage.

The air passage may have a diameter smaller than a diameter of the drainpassage.

The drain line may include an outlet port protruded at the pump case,and a drain hose including one end connected to the outlet port and theother end extended to an outside.

In accordance with another aspect of the present disclosure, a drainpump includes a pump case, a pumping motor, a drain hose, an air outletport, an air inlet port, and an air passage. The pump case may beconfigured to accommodate washing water. The pumping motor may beprovided at one end of the pump case to pump the washing water to anoutside. The drain hose may be connected to the pump case while beingadjacent to the pumping motor such that the washing water pumped by thepumping motor flows to an outside. The air outlet port may be formed ata side of an upper portion of the pump case to discharge air, the sideadjacent to the pumping motor. The air inlet port may protrude at thedrain hose. The air passage may connect the air outlet port to the airinlet port.

The air may naturally flow from the air outlet port to the air inletport due to the difference in pressure between the drain hose and thepump case, the difference in pressure caused by the difference invelocity between the washing water flowing in the drain hose and thewashing water flowing in the pump case.

In accordance with another aspect of the present disclosure, a drainpump includes a pump case, a pumping motor, a drain hose, an air outletport and an air passage. The pump case may be configured to accommodatewashing water. The pumping motor may be provided at a portion of thepump case to generate a driving force to allow the washing water to beforcedly discharged to an outside. The drain hose may be connected tothe portion of the pump case, at which the pumping motor is provided, toguide the washing water to an outside. The air outlet port may protrudeat an upper side of the portion of the pump case, at which the pumpingmotor is provided, to discharge air. The air passage may have one endconnected to the air outlet port and the other end connected to thedrain hose.

The air passage may be integrally formed with the drain hose.

In accordance with another aspect of the present disclosure, withrespect to a washing machine provided with a tub, a drain pump to pumpwashing water in the tub, and a drain hose configured to allow thewashing water pumped by the drain pump to flow therethrough fordrainage, the drain pump includes a washing water inlet compartment, adrain pump compartment, an air outlet port, and an air passage. Thewashing water inlet compartment may be configured to enable the washingwater to be introduced thereinto from the tub. The drain pumpcompartment may be provided with a suction port to draw the washingwater in the washing water inlet compartment, and an outlet portincluding a drain hose, which is configured to drain the washing water,connected thereto. The air outlet port may be protruded at an upperportion of the drain pump compartment. The air passage may connect theair outlet port to the drain hose.

The drain hose may include an air inlet port protruded at the drainhose, wherein the air passage may have one end connected to the airoutlet port and the other end connected to the air inlet port.

The other end of the air passage may be integrally formed with the drainhose.

In accordance with another aspect of the present disclosure, a washingmachine includes a cabinet, a tub, a drain pump, a drain line and an airpassage. The tub may be disposed at an inside the cabinet to accommodatewashing water. The drain pump may be disposed at a lower portion of thetub to drain the washing water contained in the tub. The drain line maybe connected to the drain pump to guide the washing water, which ispumped by the drain pump, to an outside the cabinet. The air passage mayconnect the drain pump to the drain line to discharge air contained inthe drain pump.

The drain pump may include an air outlet port protruded upward, at thedrain pump, and the drain line comprises an air inlet port protrudedupward, at the drain line, wherein one end of the air passage may beconnected to the air outlet port and the other end of the air passage isconnected to the air inlet port.

The drain pump may include an air outlet port protruded upward, at thedrain pump, wherein one end of the air passage is connected to the airoutlet port and the other end of the air passage is integrally formedwith the drain line.

According to embodiments of the present disclosure, the air outlet portis formed at an upper side of the drain pump compartment, and the airoutlet port is connected to the drain hose to easily remove the air inthe drain pump.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the disclosure will become apparent andmore readily appreciated from the following description of embodiments,taken in conjunction with the accompanying drawings of which:

FIG. 1 is a cross-sectional view illustrating the configuration of awashing machine in accordance with an embodiment of the presentdisclosure.

FIG. 2 is a perspective view illustrating a drain pump and a drain hoseof the washing machine in accordance with an embodiment of the presentdisclosure.

FIG. 3 is a perspective view illustrating the drain pump of the washingmachine of FIG. 1.

FIG. 4 is a view illustrating a pump case of the drain pump of FIG. 3.

FIG. 5 is a view illustrating the drain hose of FIG. 3.

FIG. 6 is a cross-sectional view illustrating the pump case taken alongline I-I.

FIG. 7 is a perspective view illustrating a drain pump in accordancewith another embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

Referring to FIGS. 1 and 2, a washing machine 1 includes a cabinet 10forming the exterior of the washing machine 1, a tub 20 disposed at aninside the cabinet 10, a rotating tub 30 rotatably disposed at the tub20, and a motor 40 to drive the rotating tub 30.

The cabinet 10 includes a plurality of frames 10 a, 10 b, and 10 cincluding a front side frame 10 a forming the front surface of thecabinet 10, lateral side frames 10 c forming the lateral surfaces andthe rear surface of the cabinet 10, and a lower side frame 10 b framingthe lower surface of the cabinet 10.

The lower side frame 10 b is provided at a front side thereof with apredetermined portion that is bent upward to be coupled to the frontside frame 10 a.

The cabinet 10 is provided at a front surface thereof with an inlet 11through which a laundry is input into the rotating tub 30. The inlet 11is open/closed by the door 12 installed at the front surface of thecabinet 10.

The tub 20 is supported by a damper 25. The damper 25 connects thebottom surface of an inner side of the cabinet 10 to an outer surface ofthe tub 20.

A water supply pipe 50 to supply the tub 20 with washing water isinstalled at an upper portion of the tub 20. One side of the watersupply pipe 50 is connected to an outside water supply source (notshown), and the other side of the water supply pipe 50 is connected to adetergent dispensing apparatus 52.

The detergent dispensing apparatus 52 is connected to the tub 20 througha connection pipe 54. The water supplied through the water supply pipe50 is supplied to an inside the tub 20 together with detergent via thedetergent dispensing apparatus 52.

The rotating tub 30 includes a cylindrical part 31, a front side panel32 disposed at a front side of the cylindrical part 31, and a rear sidepanel 33 disposed at a rear side of the cylindrical part 31. The frontside panel 32 has an opening 32 a through which a laundry isinput/withdrawn. The rear side panel 33 is connected to a driving shaft41 configured to transmit a driving force of the motor 40.

A plurality of through-holes 34 is formed through a circumference of therotating tub 30 for circulation of the washing water, so that an innerspace of the rotating tub 30 communicates with an inner space of the tub20.

A plurality of lifters 35 is installed at an inner circumferentialsurface of the rotating tub 30 to enable the ascending and descending oflaundry when the rotating tub 30 rotates.

The driving shaft 41 has one end connected to the rear side panel 33 ofthe rotating tub 30, and the other end extended to an outside the tub20. When the motor 40 drives the driving shaft 41, the rotating tub 30connected to the driving shaft 41 rotates about the driving shaft 41.

A bearing housing 42 rotatably supporting the driving shaft 41 isinstalled at a rear wall of the tub 20. The bearing housing 42 may beformed using an aluminum alloy. The bearing housing 42 may be insertedinto the rear wall of the tub 20 when the tub 20 is formed through aninjection molding. A plurality of bearings 43 is installed between thebearing housing 42 and the driving shaft 41 to enable a smooth rotationof the driving shaft 41.

During a washing cycle, the motor 40 rotates the rotating tub 30 inreverse/forward directions at a low speed. As the rising and falling ofthe laundry at an inside the rotating tub 30 is repeated, the dirt onthe laundry is removed.

During a spin-dry cycle, the motor 40 rotates the rotating tub 30 in onedirection at a high speed, so that water is separated from the laundryby a centrifugal force acting on the laundry.

A drain pump 100 to pump the washing water stored in the tub 20 isinstalled at a lower portion at an inside of the cabinet 10. The drainpump 100 is connected to the outside through a drain hose 60.

The drain pump 100 is exposed to the front surface of the cabinet 10through a through-hole 13 that is provided at a portion where theprotrusion of the lower side frame 10 b overlaps a lower end of thefront side frame 10 a.

The drain hose 60 is coupled to an inner side of the cabinet 10 by ahose wire 92 and a hose holder 91 while preventing the drain hose 60from interfering with other components at an inside the cabinet 10. Thedrain hose 61 is guided to an outside by a hose guide 90.

FIG. 3 is a perspective view illustrating the drain pump of the washingmachine of FIG. 1. FIG. 4 is a view illustrating a pump case of thedrain pump of FIG. 3. FIG. 5 is a view illustrating the drain hose ofFIG. 3. FIG. 6 is a cross-sectional view illustrating the pump casetaken along line I-I. The pump case illustrated on the FIG. 6 has thepump filter omitted therefrom.

Referring to FIGS. 3 to 6, a drain pump 100 a includes a washing waterinlet compartment 111, a pump case 110 including a drain pumpcompartment 120 and a bubble generating compartment 130, and a pumpfilter 140 configured to be inserted into the washing water inletcompartment 111. The drain pump compartment 120 and the bubblegenerating compartment 130 are disposed opposite to each other whileinterposing the washing water inlet compartment 111 thereinbetween.

A bubble generating motor 131 is disposed at a side of the pump case 110adjacent to the bubble generating compartment 130. A circulationimpeller 132 is connected to the bubble generating motor 131. Thecirculation impeller 132 is disposed at an inside the bubble generatingcompartment 130.

The bubble generating compartment 130 is provided, at an upper portionof the bubble generating compartment 130, with a circulation port 134that protrudes upward to circulate the washing water 20 to an inside ofthe tub 20. A circulation pipe 80 is connected to the circulation port134.

As the circulation impeller 132 is rotated by the bubble generatingmotor 131, the washing water in the washing water inlet compartment 111is drawn into the shaft direction. Bubbles are generated by mixing airwith washing water by the difference in pressure in the bubblegenerating compartment 130 due to the pressure drop caused by theflowing of washing water. The bubbles are introduced into the tub 20through the circulation port 134 and the circulation pipe 80 by thecirculation impeller 132.

The pump filter 140 is mounted at the front surface of the washing waterinlet compartment 111 to remove foreign substance on the washing waterthat is introduced into the tub 20.

The pump filter 140 is provided in the form of a cylinder having ahollowness, and includes a head part 141 and a body part 145. If thepump filter 140 is mounted on the pump case 110, the body part 145 ofthe pump filter 140 is accommodated at an inside the washing water inletcompartment 111 of the pump case 110.

The head part 141 is provided at a lateral side thereof with a secondscrew thread 143 that is screwed to the pump case 110. The head part 141is provided at a front side thereof with a grip 142 that is grippable bya user to rotate the head part 141.

The washing water inlet compartment 111 is provided at a front sidethereof with an entry 116 into which the pump filter 140 is inserted. Arim of the entry 116 is provided with a first screw thread 117 having ashape corresponding to the second screw thread 143 of the pump filter140.

The head part 141 of the pump filter 140 is exposed to the front surfaceof the cabinet 10 by the through-hole 13 that passes through the lowerside frame 10 b and the front side frame 10 a. A cover (not shown) tocover the through-hole 13 is coupled to the front side frame 10 a.

The user opens the cover (not shown) to expose the head part 141, andholds the grip 142 to rotate the head part 141 , thereby separating thepump filter 140 from the drain pump 100 a so as to replace or clean thepump filter 140.

The pump case 110 is coupled to a lower side frame 10 b through a mountpart 150 that is formed at a lower portion of the pump case 110. As themount part 150 is inserted into a coupling groove 14 which is formed ata portion of the lower side frame 10 b corresponding to the mount part150, the pump case 110 is coupled to the lower side frame 10 b.

Fastening holes 155 and 156 are formed at a lower portion of an outerside of the bubble generating compartment 130 and the drain pumpcompartment 120 of the pump case 110 such that the pump case 110 iscoupled to the protruding portion of the lower side frame 10 b. If afastening member (not shown) is coupled to the fastening holes 155 and156 through the protruding portion of the lower side frame 10 b, theprotruding portion of the lower surface frame 10 b is coupled to thepump case 110.

Water remaining in the pump case 110 is discharged through a residualwater outlet port 180 that is formed at a lower portion of the pump case110. One end of a residual water hose (not shown) is connected to theresidual water outlet port 180, and the other end of the residual waterhose is exposed to the front surface of the cabinet 10 through thethrough-hole 13. Accordingly, a user removes the water remaining in thepump case 110 by use of the residual water hose (not shown) exposed tothe front surface of the cabinet 10.

An inlet port 114 is provided on the washing water inlet compartment 111while protruding to the rear side of the washing water inlet compartment111. The washing water inlet compartment 111 communicates with the inletport 114. A connection part connecting the washing water inletcompartment 111 to the inlet port 114 has an inlet hole 115 that isconfigured to connect the washing water inlet compartment 111 to theinlet port 114.

An inlet hose 70 is connected to the inlet port 114 such that thewashing water in the tub 20 is introduced to the washing water inletcompartment 111 by passing through the inlet hose 70 and the inlet port114 via the inlet hole 115.

An impeller 122 to forcedly draw the washing water in the washing waterinlet compartment 111 and to discharge the drawn washing water, isinstalled in the drain pump compartment 120 of the pump case 110. Thepumping motor 121 is connected to the impeller 122. The impeller 122,which is rotated by the pumping motor 121, draws in the washing water ofthe washing water inlet compartment 111 in the shaft direction, anddischarges the washing water in the radial direction.

A drain hose 60 a is connected to the drain pump compartment 120 andconfigured to guide and drain the washing water pumped by the impeller122 to the outside the cabinet 10.

A first suction port 123 is formed between the drain pump compartment120 and the washing water inlet compartment 111, and serves as apassage, into which the washing water in the washing water inletcompartment 111 is drawn.

A second suction port 133 is formed between the bubble generatingcompartment 130 and the washing water inlet compartment 111, and servesas a passage, into which the washing water in the washing water inletcompartment 111 is drawn.

An outlet port 124 to discharge the washing water pumped by the impeller122 is formed on the drain pump compartment 120 while extending to therear side of the drain pump compartment 120.

The drain hose 60 a is connected to the outlet port 124.

The outlet port 124 and the drain hose 60 a form a drain line configuredto guide the washing water from the drain pump compartment 120 to anoutside.

In order to remove the air, which is generated by collision between theimpeller 122 and the washing water, and the air, which is introducedwhen the washing water is introduced into the washing water inletcompartment 111, from the pump case 110, an air outlet port 160 isformed on the drain pump compartment 120 while protruding upward.

The washing water introduced into the washing water inlet compartment 11naturally moves. However, the washing water, after passing through thewashing water inlet compartment 111 and the drain pump compartment 120,is drained through the outlet port 124 and the drain hose 60 a whilebeing forcedly discharged by the impeller 122 at a high speed.Accordingly, the amount of washing water being discharged is larger thanthat of washing water being introduced.

Due to the difference in amount between the washing water beingintroduced and the washing water being discharged, the upper portion ofthe drain pump compartment 120 is filled with a larger amount of airthan the washing water inlet compartment 111 is.

Further, the velocity of the washing water is increased by the impellerrotating at a high speed, and the pressure of the drain pump compartment120 is decreased. If the pressure falls below the saturated vaporpressure of the washing water, cavitation phenomenon that generates airbubbles dissolved in the washing water occurs. The air generated in thedrain pump compartment 120 fills the drain pump compartment 120.

The air filled in the upper portion of the drain pump compartment 120causes an abnormal oscillation and noise, and degrades the function ofthe drain pump 100 a. Accordingly, there is a need for removing the air.By forming the air outlet port 160 at the upper portion of the drainpump compartment 120 filled with the air, the discharging of air iseffectively achieved.

One end of the drain hose 60 a, as described above, is guided to anoutside the cabinet 10 by the hose guide 90. The other end of the drainhose 60 a is provided with a connection part 62 a configured to connectthe other end of the drain hose 60 a to the outlet port 124.

An air inlet port 61 a is formed while protruding at the drain hose 60a, and the air outlet port 160 is connected to the air inlet port 61 athrough an air passage 170 a. One end of the air passage 170 a isconnected to the air outlet port 160, and the other end of the airpassage 170 a is connected to the air inlet port 160.

The air inlet port 61 a according to an embodiment of the presentdisclosure has been described as being formed on the drain hose 60 a.However, the aspect of the present disclosure is not limited thereto,and the air inlet port 61 a may be formed on the connection part 62 a orthe air outlet port 160. Further, one end of the air passage 170 a maybe connected directly the outside to discharge air from the air outletport 160. The air passage 170 a may be connected to the outside and theair inlet port 61 a to improve the discharge of the air from the airoutlet port 160.

Hereinafter, the flow of the washing water and the air will bedescribed.

As the impeller 122 rotates, the washing water moves from the washingwater inlet compartment 111 to the drain pump compartment 120 via thefirst suction port 123. Thereafter, the washing water, by passingthrough an outlet hole 125 of the drain pump compartment 120, isdischarged to an outside the cabinet 10 via the outlet port 124 and thedrain hose 60 a.

The washing water in the drain pump compartment 120 is moved to theoutlet port 124 and the drain hose 60 a by the impeller 122 at a highspeed. In this case, the washing water flowing from the washing waterinlet compartment 111 to the drain pump compartment 120, that is, thewashing water passing through the first suction port 123, flows at avelocity higher than that of the washing water passing through theoutlet port 124 and the drain hose 60 a.

Since the pump case 110 is not substantially different in height fromthe drain hose 60 a, when the heights of the pump case 110 and the drainhose 60 a are assumed to be same, the pressure of the drain hose 60 a islower than the pressure of the first suction port 123 according toBernoulli's principle.

u ²/2+g·h+ρ/=constant (Bernoulli's principle)

That is, the pressure of the air outlet port 160 is higher than thepressure of the air inlet port 61 a.

As described above, the difference in amount between the washing waterbeing discharged and the washing water being introduced as well as thecavitation phenomenon cause the upper portion of the drain pumpcompartment 120 to be filled with air. The difference in pressure allowsthe air to flow from the air outlet port 160 to the air inlet port 61 athrough the air passage 170 a.

According to the above structure as such, the air in the drain pump 100a is naturally discharged to an outside the cabinet 10 through the drainhose 60 a.

Therefore, the air is removed from the drain pump 100 a, in particular,from the drain pump compartment 120, so that the vibration and noise areremoved, and the efficiency of the drain pump is enhanced.

FIG. 7 is a perspective view illustrating a drain pump in accordancewith another embodiment of the present disclosure.

The description of the same reference numerals will be assigned toelements identical to the elements according to the previous embodiment,and description thereof will be omitted.

Referring to FIG. 7, a drain pump 100 b includes a washing water inletcompartment (111 in FIG. 6), a pump case 110 provided with a drain pumpcompartment (120 in FIG. 6) and a bubble generating compartment (130 inFIG. 6), and a pump filter 140 inserted into the washing water inletcompartment 111.

The bubble generating motor 131 is connected to one end of the pump case110 including the bubble generating compartment 130. The circulationport 134 is formed at the upper portion of the bubble generatingcompartment 130. The circulation pipe 80 is connected to the circulationport 134.

The pump filter 140 is inserted into the front surface of the drain pump100 b.

The washing inlet compartment (111 in FIG. 6) is formed in the center atan inside of the drain pump 100 b. The inlet port 114 is provided on thewashing water inlet compartment 111 while protruding to the rear side ofthe washing water inlet compartment 111. An inlet hose 70 is connectedto the inlet port 114 such that the washing water in the tub 20 isintroduced to the washing water inlet compartment 111. One end of theinlet hose 70 is connected to the inlet port 114 and the other end ofthe inlet hose 70 is connected to the tub (20 in FIG. 1).

The washing water in the tub 20 is introduced into the washing waterinlet compartment 111 in the drain pump 100 b through the inlet hose 70.

The drain pump compartment (120 in FIG. 6) is formed at the opposite endof the pump case 110 including the bubble generating motor 131. Thepumping motor 121 provided with the impeller (122 in FIG. 3) is mountedon the drain pump compartment 120.

As described above, the upper portion of the inner side of the drainpump compartment 120 is filled with air. Accordingly, the air outletport 160 is provided while protruding at the upper portion of the outerside of the drain pump compartment 120 to discharge air.

A drain hose 60 b is provided with a connection part 62 b configured toconnect to the outlet port 124 that protrudes to the rear side of thepump case 110.

An air passage 170 b branches from the drain hose 60 b while beingintegrally formed with the drain hose 60 b. The air passage 170 b isconnected to the air outlet port 160.

As described above, since the velocity of the washing water at the drainhose 60 b is higher than that of the washing water in the drain pumpcompartment 120, the pressure in the pump case 110 is higher than thepressure in the drain hose 60 b according to Bernoulli's principle.

Accordingly, the air in the upper portion of the drain pump compartment120 moves along from the air outlet port 160 to the drain hose 60 b. Theair reached to drain hose 60 b is discharged to an outside of thecabinet 10 together with the washing water.

As the air in the pump case 110 is reduced, the vibration and noiseoccurring in the drain pump is reduced, and the efficiency of the drainpump is enhanced.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the disclosure, the scope of which is definedin the claims and their equivalents.

What is claimed is:
 1. A drain pump comprising: a washing water inletcompartment; a drain pump compartment configured to pump washing watercontained in the washing water inlet compartment to an outside; asuction port provided between the washing water inlet compartment andthe drain pump compartment to move the washing water from the washingwater inlet compartment to the drain pump compartment; a drain line toconnect the drain pump compartment to the outside, to discharge thewashing water; and an air outlet port provided on the drain pumpcompartment to discharge air contained in the drain pump compartment,wherein the air outlet port is connected to the drain line.
 2. The drainpump of claim 1, wherein air naturally flows from the air outlet port tothe drain line due to the difference in pressure between the drain pumpcompartment and the drain line.
 3. The drain pump of claim 1, whereinthe air outlet port protrudes at an upper portion of the drain pumpcompartment.
 4. The drain pump of claim 1, further comprising an airinlet port provided on the drain line, wherein the air outlet port isconnected to the air inlet port.
 5. The drain pump of claim 4, furthercomprising an air passage to connect the air outlet port to the airinlet port.
 6. The drain pump of claim 5, wherein the air passagecomprises a rubber hose.
 7. The drain pump of claim 4, wherein the airinlet port is integrally formed with the drain line.
 8. The drain pumpof claim 4, wherein the air inlet port is separately formed with thedrain line and coupled to the drain line.
 9. The drain pump of claim 1,wherein the drain line comprises a drain passage connected to the drainpump compartment, and an air passage connected to the air outlet port.10. The drain pump of claim 9, wherein the air passage is branched fromthe drain passage.
 11. The drain pump of claim 9, wherein the airpassage is integrally formed with the drain passage.
 12. The drain pumpof claim 9, wherein the air passage has a diameter smaller than adiameter of the drain passage.
 13. The drain pump of claim 1, whereinthe drain line comprises an outlet port protruded at the pump case, anda drain hose including one end connected to the outlet port and theother end extended to an outside.
 14. A drain pump comprising: a pumpcase configured to accommodate washing water; a pumping motor providedat one end of the pump case to pump the washing water to an outside; adrain hose connected to the pump case while being adjacent to thepumping motor such that the washing water pumped by the pumping motorflows to an outside; an air outlet port formed at a side of an upperportion of the pump case to discharge air, the side adjacent to thepumping motor; an air inlet port protruded at the drain hose; and an airpassage to connect the air outlet port to the air inlet port.
 15. Thedrain pump of claim 14, wherein air naturally flows from the air outletport to the air inlet port due to the difference in pressure between thedrain hose and the pump case, the difference in pressure caused by thedifference in velocity between the washing water flowing in the drainhose and the washing water flowing in the pump case.
 16. A drain pumpcomprising: a pump case configured to accommodate washing water; apumping motor provided at a portion of the pump case to generate adriving force to allow the washing water to be forcedly discharged to anoutside; a drain hose connected to the portion of the pump case, atwhich the pumping motor is provided, to guide the washing water to anoutside; an air outlet port protruded at an upper portion of the pumpcase, at which the pumping motor is provided, to discharge air; and anair passage including one end connected to the air outlet port and theother end connected to the drain hose.
 17. The drain pump of claim 16,wherein the air passage is integrally formed with the drain hose.
 18. Awashing machine provided with a tub, a drain pump to pump washing waterin the tub, and a drain hose configured to allow the washing waterpumped by the drain pump to flow therethrough, wherein the drain pumpcomprises: a washing water inlet compartment into which the washingwater is introduced from the tub; a drain pump compartment provided witha suction port to draw the washing water in the washing water inletcompartment, and an outlet port connected to a drain hose which isconfigured to drain the washing water; an air outlet port protruded atan upper portion of the drain pump compartment; and an air passage toconnect the air outlet port to the drain hose.
 19. The washing machineof claim 18, wherein the drain hose comprises an air inlet portprotruded at the drain hose, wherein the air passage includes one endconnected to the air outlet port and the other end connected to the airinlet port.
 20. The washing machine of claim 18, wherein the other endof the air passage is integrally formed with the drain hose.
 21. Awashing machine comprising: a cabinet; a tub disposed at an inside thecabinet to accommodate washing water; a drain pump disposed at a lowerportion of the tub to drain the washing water contained in the tub; adrain line connected to the drain pump to guide the washing water, whichis pumped by the drain pump, to an outside the cabinet; and an airpassage to connect the drain pump to the drain line to discharge aircontained in the drain pump.
 22. The washing machine of claim 21,wherein the drain pump comprises an air outlet port protruded upward, atthe drain pump, and the drain line comprises an air inlet port protrudedupward, at the drain line, wherein one end of the air passage isconnected to the air outlet port and the other end of the air passage isconnected to the air inlet port.
 23. The washing machine of claim 21,wherein the drain pump comprises an air outlet port protruded upward, atthe drain pump, wherein one end of the air passage is connected to theair outlet port and the other end of the air passage is integrallyformed with the drain line.